Field of the Invention
The present invention relates to a zoom lens and an image pickup apparatus using the same.
Description of the Related Art
A zoom lens to be used in an image pickup apparatus is desired to be small-sized, and moreover, it is desired that various aberrations are corrected favorably. On the other hand, an image pickup element to be used in an image pickup apparatus is preferred to have a high sensitivity and a large number of pixels. Therefore, a size of the image pickup element (a size of a light receiving surface) becomes large. For such reasons, in a zoom lens, in addition to be small-sized and having favorable correction of various aberrations, it is desired that the zoom lens is capable to cope with an image pickup element of a large size.
As the size of the image pickup element becomes large, a size of an image formed on the image pickup element also becomes large. To be able to cope with the image pickup element of a large size means various aberrations in a peripheral portion (a portion of a large image height) are to be corrected favorably even in a case in which, the size of the image has become large.
As a zoom lens which realizes the abovementioned demand, a zoom lens of negative-lead type has been known. In the negative-lead type zoom lens, a lens unit having a negative refractive power is disposed nearest to an object. As the negative-lead type zoom lens, a zoom lens that includes two lens units and a zoom lens that includes three lens units are available. The zoom lens that includes two lens units includes in order from an object side, a lens unit having a negative refractive power and a lens unit having a positive refractive power.
Moreover, as the zoom lens that includes three lens units, a zoom lens disclosed in Japanese Patent Application Laid-open Publication No. 2012-22019 is available. The zoom lens disclosed in Japanese Patent Application Laid-open Publication No. 2012-22019 includes in order from the object side, a first lens unit having a negative refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power.